Brunhes–Matuyama reversal

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The Brunhes–Matuyama reversal, named after Bernard Brunhes and Motonori Matuyama, was a geologic event, approximately 781,000 years ago, when the Earth's magnetic field last underwent reversal.[1][2] Estimations vary as to the abruptness of the reversal. A 2004 paper estimated that it took over several thousand years;[3] a 2010 paper estimated that it occurred more quickly,[4][5][6] perhaps within a human lifetime;[7] a 2019 paper estimated that the reversal lasted 22,000 years.[8][9]

The apparent duration at any particular location can vary by an order of magnitude, depending on geomagnetic latitude and local effects of non-dipole components of the Earth's field during the transition.[3]

The Brunhes–Matuyama reversal is a Global Boundary Stratotype Section and Point (GSSP), selected by the International Commission on Stratigraphy as a marker for the beginning of the Middle Pleistocene, also known as the Ionian Stage.[10] It is useful in dating ocean sediment cores and subaerially erupted volcanics. There is a highly speculative theory that connects this event to the large Australasian strewnfield (c. 790,000 years ago),[11] although the causes of the two are almost certainly unconnected and only coincidentally happened at the same time.

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  1. ^ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G., eds. (2004). A Geological Time Scale (3rd ed.). Cambridge: Cambridge University Press. p. 28. ISBN 978-0521786737.
  2. ^ "Global chronostratigraphical correlation table for the last 2.7 million years". International Commission on Stratigraphy. Retrieved 31 March 2014.
  3. ^ a b Bradford M. Clement (8 April 2004). "Dependence of the duration of geomagnetic polarity reversals on site latitude". Nature. 428 (6983): 637–40. Bibcode:2004Natur.428..637C. doi:10.1038/nature02459. PMID 15071591.
  4. ^ Witze, Alexandra (Sep 2, 2010). "Geomagnetic field flip-flops in a flash". ScienceNews. Retrieved 3 September 2010.
  5. ^ Coe, R.S.; Prévot, M.; Camps, P. (20 April 1995). "New evidence for extraordinarily rapid change of the geomagnetic field during a reversal" (PDF). Nature. 374 (6524): 687. Bibcode:1995Natur.374..687C. doi:10.1038/374687a0. Archived from the original (PDF) on 31 July 2010.
  6. ^ Bogue, S. W.; Glen, J. M. G. (2010). "Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow". Geophysical Research Letters. 37 (21): L21308. Bibcode:2010GeoRL..3721308B. doi:10.1029/2010GL044286. S2CID 129896450.
  7. ^ Leonardo Sagnotti; Giancarlo Scardia; Biagio Giaccio; Joseph C. Liddicoat; Sebastien Nomade; Paul R. Renne; Courtney J. Sprain (21 July 2014). "Extremely rapid directional change during Matuyama-Brunhes geomagnetic polarity reversal". Geophys. J. Int. 199 (2): 1110–1124. Bibcode:2014GeoJI.199.1110S. doi:10.1093/gji/ggu287.
  8. ^ Singer, Brad S.; Jicha, Brian R.; Mochizuki, Nobutatsu; Coe, Robert S. (August 7, 2019). "Synchronizing volcanic, sedimentary, and ice core records of Earth's last magnetic polarity reversal". Science Advances. 5 (8): eaaw4621. doi:10.1126/sciadv.aaw4621. ISSN 2375-2548. PMC 6685714. PMID 31457087.
  9. ^ Science, Passant; Rabie (August 7, 2019). "Earth's Last Magnetic-Pole Flip Took Much Longer Than We Thought". Retrieved August 8, 2019.
  10. ^ "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Archived from the original on 15 November 2012. Retrieved 31 March 2014.
  11. ^ Glass, B. P., Swincki, M. B., & Zwart, P. A. (1979). "Australasian, Ivory Coast and North American tektite strewnfields – Size, mass and correlation with geomagnetic reversals and other earth events" Lunar and Planetary Science Conference, 10th, Houston, Tex., March 19–23, 1979, pp. 2535–2545.

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